[GRASS-user] fill gaps

GRASS GRASS user
1

Dear grass user,

"I am doing some post-classification smoothing. First areas lesser than

1ha are removed using r.reclass.area and then gaps (NULL cells)
filled using r.filldir."

For filling nulls, r.fillnulls or other methods may be used.

The intended purpose of r.filldir is different and has been briefly explained in the manual i.e. to create depressionless elevation map and flow direction map.

In the manual, it is advised to read the book “Software Tools to Extract Structure from Digital Elevation Data for Geographic Information System Analysis” by S.K. Jenson and J.O. Domingue (1988)." and it’s a good idea.

In the book, you may read this :

“Previous research has almost universally recognized that depressions,
areas surrounded by higher elevation values, in the DEM data are the
nemesis of determining hydrologic flow directions because the
depressions must fill before the flow can continue.”

I have googled it for you " book".

"http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CEMQFjAA&url=http%3A%2F%2Fblogs.halcrow.com%2Fgeospatial%2Fwp-content%2Fuploads%2F2010%2F07%2FJenson_Domingue_1988_EROS.pdf&ei=AU7fTqTKK4TOrQeGiqmBCQ&usg=AFQjCNGft9-9VxK4GR2WAoO10uzw1Fx43Q&sig2=pxFpawG5wrcyTcA8DqCDUQ ".

(attachments)

Jenson_Domingue_1988_EROS.pdf (230 KB)